Flight number record
UA 1835
United Airlines · Denver to San Diego
- Route
- DEN → SAN
- Departs
- 21:00
- Flights
- 258
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s UA 1835, check with United Airlines.
UA 1835 draws a C+. About one flight in three arrives at least 15 minutes late, and the typical late arrival is about an hour behind schedule. Build slack into anything you connect to. That rests on 258 flights, with a median arrival 4 minutes late.
The national on-time rate over the same period is 77.6%, so UA 1835 runs 12 points behind the country as a whole. Across a thousand flights that is about 119 extra late arrivals.
Key figures
On time
65.7%
Arrivals under 15 minutes late, of 254 completed flights
Avg delay
63 min
Across delayed arrivals only, not all flights
Cancelled
0.78%
National rate is 1.81%
1 hour+ late
11.0%
National rate is 8.1%
These figures cover 258 flights between July 2025 and June 2026. Beyond the headline rate, 11.0% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Schedule
When UA 1835 flies
UA 1835 flies DEN to SAN without a single fixed slot. Its most common scheduled departure was 21:00, used on 96 of 258 flights, with 20:50 (94 flights) and 21:05 (33 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 21:0096 flights37.2%
- Departs 20:5094 flights36.4%
- Departs 21:0533 flights12.8%
Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 21:00 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.5%, and UA 1835 runs 5 points worse at 65.7%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
Against the route
UA 1835 next to DEN to SAN
Every carrier on DEN to SAN combined arrived on time 75.6% of the time across 5,949 flights, so UA 1835 is 10 points behind it. United flew 2,081 flights on the same city pair under all its flight numbers, including this one, and those ran 79.8% on time. Across its whole network United Airlines managed 79.0%, which this flight trails by 13 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1835thin sample | 258 | 65.7% | 63 min | 0.78% | C+ |
| All United Airlines on DEN–SAN | 2,081 | 79.8% | 59 min | 0.48% | B+ |
| All carriers on DEN–SAN | 5,949 | 75.6% | 56 min | 0.66% | B+ |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | B |
Across the year
UA 1835 quarter by quarter
UA 1835 did not run the same all year. Its best quarter was Apr–Jun 2026 at 76.7% on time and its weakest Jul–Sep 2025 at 45.2%, a swing of 32 points on roughly 65 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202576 flights45.2%
- Oct–Dec 202568 flights73.1%
- Jan–Mar 202654 flights72.2%
- Apr–Jun 202660 flights76.7%
Scale runs 35% to 80%. Rows with fewer than 30 flights show a dash.
By weekday, UA 1835 did best on Friday at 80.0% on time and worst on Thursday at 56.0%. Each day rests on about 37 flights, so a gap of 24 points is worth noticing but could still narrow in another year.
Delay causes
Why UA 1835 runs late
One category carries most of the weight here. Late-arriving aircraft accounts for 45% of the 5,472 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 45%Late-arriving aircraft
- 34%Carrier
- 20%National Airspace System
- 1%Extreme weather
45% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 5,472 reported delay minutes here, that single category outweighs weather by 45 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 5,472 delay minutes reported on UA 1835.
Cancellations are rare at 0.78%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and routes
What a delay on this flight costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 11.0% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
The 853 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The same number turns up on five other city pairs in the data, including LGA to DEN (53), FCA to DEN (38) and DFW to DEN (26), but none flew often enough under UA 1835 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to DEN to SAN only.
One caution: this is a thin sample. 258 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking UA 1835
For a booking, UA 1835 is one of the weaker ways to fly DEN to SAN: 10 points below the route as a whole. If the schedule allows, compare it with the other departures listed on the route page before settling on this one.
Related
Where to go next
- DEN to SAN, every carrier and departure
- SAN to DEN, the return direction
- United Airlines 540 on the same route65.7%
- United Airlines 1302 on the same route88.0%
- United Airlines 2309 on the same route90.3%
- United Airlines 1940 on the same route82.0%
- United Airlines 1281 on the same route84.6%
- Denver International (DEN) delay statistics
- San Diego International (SAN) delay statistics
- United Airlines on-time record
- Every United Airlines flight number with a record
- The most and least reliable flight numbers in the US
- Why the first flight of the morning is statistically safest
A flight number here means United Airlines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.